Brake Controller has Constant Power Output and is Draining the Battery on the Truck  

Question:

Helpful Expert Reply:

Brake controllers do send a little power back to check for a trailer but it should not be that much. You will either have an issue inside the brake controller or there is a short somewhere else that is causing a draw. To determine which, you will need to disconnect the trailer from the truck and use a circuit tester to test a few things.

You mentioned installing a new trailer connector but if the wires have corrosion on them that can cause a short and draw power. Make sure the vehicle and trailer side connectors are clean and free of corrosion inside and out.

In the truck, sever the blue wire a few inches from the back of the brake controller and use your circuit tester to test the end coming out of the controller. It should only show power when the manual override is used. If it shows power at any other time then there is likely an issue inside the controller and it will need to be replaced. You can try fully applying the manual override and letting it snap back into place several times to clean the contacts inside to see if that helps.

If this issue only happens with the trailer connected, it could be an issue with the trailer wiring. Inspect the trailer wiring for any copper strands touching bare metal. Also check to make sure the grounds are attached to clean and corrosion free bare metal surfaces. Visually inspect the magnets and if you see the windings coming through they will need to be replaced.

To further test the magnets and for more brake controller information I have included some FAQ article links that should help you.

expert reply by: Michael H

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